Longitudinal Survey of Lymphocyte Subpopulations in the First Year of Life

Abstract

Age-matched reference values for lymphocyte subpopulations are generally obtained via cross-sectional studies, whereas patients are followed longitudinally. We performed a detailed longitudinal analysis of the changes in lymphocyte subpopulations in a group of 11 healthy infants followed from birth up to 1 y of age, with special attention for early developmental markers, markers of maturation, and markers of activation. We found that T and B lymphocytes increased at 1 and 6 wk of age, respectively. In contrast, NK cells showed a sharp decline directly after birth, suggesting that they are more important during pregnancy than thereafter. CD45RAϩ -mainly CD4 ϩ -naive T lymphocytes were high at birth, and increased further during the first year of life; they form a large expanding pool of cells, ready for participation in primary immune responses. The absolute counts of CD45RO ϩ memory T lymphocytes were similar in infants and adults, albeit with a lower level of expression of CD45RO on infant T lymphocytes. Almost all infant T lymphocytes expressed CD38 throughout the first year of life. The abundant expression of CD38 on an infant's T lymphocytes might be related to a greater metabolic need of the large population of naive untriggered cells that are continually involved in primary immune responses during the first year of life. The high B lymphocyte counts in infants mainly concerned CD38 ϩ B lymphocytes throughout the first year of life. Also, the relative frequencies of CD1c ϩ and CD5 ϩ B lymphocytes were higher throughout the first year of life than in adults. Therefore, CD1c, CD5, and CD38 could be markers of untriggered B lymphocytes. Immunophenotyping of blood lymphocyte subpopulations is an important tool in the diagnosis and follow-up of children with immune disorders. Correct interpretation of the obtained results requires knowledge of the normal development of the immune system during the first years of life.For this purpose, several sets of age-matched reference values of relative frequencies and absolute counts of lymphocyte subpopulations in childhood have been reported (1-5). Because of the higher blood lymphocyte counts in neonates and infants compared with adults (1, 6), differences in lymphocyte subpopulations are better reflected by comparison of absolute counts than relative frequencies. In that way, trends are observed that are missed when only relative frequencies are used (1). These absolute lymphocyte counts are more accurately determined by the lysed whole blood technique than by analysis after density gradient separation (7,8).To date, age-matched reference values for lymphocyte subpopulations were all obtained in cross-sectional studies. Longitudinal studies in individual children are more informative about the pattern of lymphocyte subpopulation development as a function of time. Children with immune disorders are also followed longitudinally. Therefore, it is useful to compare patient data with data from studies on longitudinal development of lymphocyte subpopulations in healthy childr...

Immune reconstitution in human immunodeficiency virus type 1-infected children with different virological responses to anti-retroviral therapy

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Reduced thymic output, increased spontaneous apoptosis and oligoclonal B cells in polyethylene glycol-adenosine deaminase-treated patients

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Influence of congenital human cytomegalovirus infection and the NKG2C genotype on NK‐cell subset distribution in children

“…3B-D). Multivariate regression analysis confirmed the relation of the NKG2C genotype with both the proportions (p = 0.001) and total numbers (p = 0.014) of NK cells, independently of age as a putative confounding variable [45,46] (Supporting Information Table 2). …”